Vibratory motor, especially for hair clippers



A ril 16, 1968 R. D. FRANZENE 3,378,705

VIBRATORY MOTOR, ESPECIALLY FOR HAIR CLIPPERS 2 Sheets-Sheet 1 Filed Oct. 8, 1965 dmdm'n April 16, 1968 R. D- FRANZENE 3,378,706

VIBRATORY MOTOR, ESPECIALLY FOR HAIR CLIPPERS Filed Oct. 8, 1965 2 Sheets-Sheet t;

STOP

DEF'LECTION United States Patent 3,378,706 VKBIRATORY MOTOR, ESPECTALLY FOR HAIR ClLlPlERS Robert D. Franzene, Chicago, lllh, assignor to Deltrol Corp, Bellwood, ML, a corporation of Delaware Filed Oct. 8, 1965, Ser. No. 494,045 Claims. (til. 310-429) This invention relates to vibratory motors, and has more particular reference to improvements in vibratory motors of the type which are used to power small electrical appliances or tools having a work performing element that must be driven at a substantially high speed. A hair clipper is one example of an electrical appliance for which the vibratory motor of this invention is especially suited.

Vibratory motors employed in hair clippers usually comprise a permanent magnet armature constrained to oscillate about a fixed pivot, electromagnetic means for effecting oscillation of the armature, and a driver on the armature which is operatively connected with the movable cutting blade of the clipper and through which oscillation of the armature is translated into reciprocatory motion of the cutting blade. The cutting blade, of course, is guided for reciprocatory motion along a defined path, and its travel is limited to a stroke that ordinarily bears a predetermined relationship to the spacing of the teeth on the cutting head of the clipper.

Heretofore, springs of various types were employed to limit the stroke of the cutting blade because of their ability to do so without creating excessive clattering noises. These springs did not act directly upon the cutting blade, but were located at opposite sides of the armature to be alternately engaged by it during oscillation thereof, to not only define the limits of armature oscillation but to also cushion the same at its limits of motion.

The springs that have been used in the past for the described purpose left much to be desired. The chief objection thereto resulted from the fact that all had constant rate characteristics, that is, the springs resisted oscillatory motion of the armature with a force that increased uniformly with the distance of armature travel from a center position thereof, until spring force equaled the torsional magnetomotive force exerted on the armature. Hence, since there are always variations in the power applied to the armature and also in friction forces between the stationary and movable blades of the cutting head, it was practically impossible to confine the armature and movable blade driven thereby to a prescribed stroke without some adjustment of the spring mounts or of the strength of the springs themselves.

With this objection in mind, it is the purpose of this invention to provide a stop device for the oscillatory armature of a vibratory motor such as is used in hair clippers and the like, comprising spring means which receives the thrust of the armature during oscillatory motion thereof, andwhich is characterized by a spring rate such that oscillatory motion of the armature in either direction away from its center position is yieldingly resisted with a force that is substantially light until the armature nears the end of its stroke, after which said resistance force rises abruptly to a value equaling the torsional magnetomotive force exerted on the armature so as to thereby define the limits of armature motion and to cushion the same as the armature reaches its limits of motion.

More specifically, it is the purpose of this invention to provide a spring stop for the oscillatory armature of a vibratory motor featuring a single spring blade having anchored ends, and a convex shoulder on the armature which rocks in opposite directions upon the spring blade from a medial zone thereof at the center position of the 3,378,766 Patented Apr. 16, 1968 armature, toward each anchored end thereof to engage portions of the blade progressively closer to its anchored ends, and which blade portions resist armature motion with a force that rises abruptly as the shoulder nears each anchored end of the blade to effect cushioned stopping of the armature and to thus define its limits of motion.

With the above and other objects in view which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiments of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate two complete examples of the physical embodiments of the invention, constructed according to the best modes so far devised for the practical application of the principles thereof, and in which:

FIGURE 1 is a plan view of a vibratory motor powered hair clipper embodying this invention, portions of the clipper housing being broken away to better illustrate the internal parts of the clipper;

FIGURE 2 is an enlarged fragmentary sectional view taken through FIGURE 1 on the plane of the line 2-2;

FIGURES 3, 4 and 5 are enlarged and more or less diagrammatic views illustrating the action of the spring stop device on the armature;

FIGURE 6 is a perspective view of the spring per se;

FIGURE 7 graphically portrays the spring rate and reaction to oscillation of the armature; and

'FlGURE 8 is a fragmentary view, similar to FIGURE 1, but illustrating a modified embodiment of the invention.

Referring now to the accompanying drawings, the numeral litl generally designates the elongated housing of a hair clipper having a cutting head at its forward end, and containing a vibratory motor 12 to effect reciprocatory motion of the cutting blade 13 of the clipper. Both the cutting head and the motor are mounted on the bot tom section 14 of the housing, and the motor is concealed by the usual cover section 15 of the housing. It should be understood that the hair clipper here shown and described represents but one example of small electric appliances to which this invention is applicable.

The movable cutting blade 13 of the clipper is guided for reciprocatory motion across the forward end of the housing in a conventional manner, as by means of a strong leaf spring 16 which also urges the movable blade down onto the stationary blade 17 of the cutting head. A notch in the rear of the cutting blade provides opposed driving abutments 18, through which driving force can be applied to the blade to effect reciprocation thereof.

The vibratory motor 12 is mounted substantially medially within the bottom section 14 of the housing, and it comprises an armature 19 at the forward end of the motor, an electromagnet core 20 having three equispaced legs 21, 22 and 23 extending forwardly toward the armature from a common crosspiece 24, and a winding 25 encircling the center leg 23 of the core.

The armature is oscillatably mounted on an upright pivot post 26 fixed in the bottom housing section and received in a bushing 27 carried by a hub portion 28 formed on the armature. The axis of the pivot post is normal to the common plane of the core legs and ahead of but in line with the center leg 23 of the core. The armature carries a permanent magnet 29 at its side adjacent to the electromagnet core, and it is provided with pole pieces 30 and 31 that extend inwardly over the magnet and cooperate with the extremities of the core legs. The extremities of the core legs have concavely curved surfaces which match with convex surfaces on the armature pole pieces, and all of these curved surfaces are concentric to the axis of the pivot post about which the armature oscillates.

The armature is caused to oscillate in response to energization of the winding 25 from a source of alternating current. A pair of leads 32 controlled by a switch are provided for that purpose. The switch is mounted in the bottom housing section rearwardly of the motor, and only its actuator 33 can be seen in FIGURE 1.

The cutting blade is driven from the armature through a drive lever 34 on the latter, which extends radially forwardly from the armature hub and has a rounded extremity received in the notch in the rear edge of the cutting blade for cooperation with the opposed abutments l8 defined thereby.

According to this invention, the oscillatory motion of the armature is limited in noiseless fashion by spring means which can comprise a single beam type leaf spring 36 which extends across the pivot axis of the armature, above its hub portion. A pair of upright anchor posts 37 and 38 fixed in the bottom housing section at opposite sides of the armature pivot post 26 nestingly engage in forwardly curled end portions 39 on the spring to hold it engaged with the surface of a forwardly facing shoulder 49 on the armature. This surface is convexly curved as at 41 at a substantially large radius having its center in line with the center leg 23 of the core and adjacent to rear of the latter. At the opposite sides of the armature, its shoulder 46 has shorter radius corners 4.2 and 4 3, which are directly rearwardly of the anchor posts 37-38.

When the armature is in its center position seen in FIGURES 1 and 3, its convex surface 41 is substantially tangent to a plane containing the armature pivot axis and passing through the anchor posts 37-32;, and said surface recedes rearwardly from said plane toward the corners 4243 of the armature shoulder.

As seen in FIGURE 6, the spring 36 normally has a slight curvature of larger radius than the surface 41 on the armature shoulder, so that its medial portion very lightly engages the shoulder on the armature when it is in its center position seen in FIGURES 1 and 3. During clockwise oscillatory motion of the armature about its pivot post, its shoulder portion leading to the corner 42 more or less rocks lengthwise along the spring toward the end thereof anchored by the post 37, as seen in FIGURE 4. Such rocking of the armature also lifts its shoulder portion across the plane containing the pivot axis and passing through the spring anchor posts, so as to deflect the spring an amount which increases gradually with the distance the armature travels away from its center position, as indicated by the numeral 45 in the FIGURE 7 graph. As a result, the spring yieldingly resists initial motion of the armature with a light force that increases very gradually as the armature shoulder engages portions of the spring more remote from the armature pivot axis, but which force abruptly increases to a value equal to the torsional magnetomotive force exerted on the armature when the corner shoulder portion d2 nears its adjacent anchor post 37. At this time, the shoulder on the armature may be said to have engagement with a portion of the spring 36 closely adjacent to its anchored end, and which portion of the spring is substantially inflexible, at least under the limited and impositive force exerted on the armature by the motor.

The numeral 46 in FIGURE 7 indicates how the spring resists oscillatory motion of the armature with a force that increases abruptly as the shoulder on the armature begins to bear on portions of the spring close to its anchor 37, and quickly stops the armature to define one of its limits of motion. The spring has the same effect upon the armature during oscillatory motion thereof in the counterclockwise direction, to stop the armature and define its other limit of motion as seen in FIGURE 5.

The spring 36 not only thus defines the limits of armature oscillation, but it very eifectively serves to cushion the armature as it reaches its limits of motion, and oscillation thereof is stopped substantially noiselessly.

Referring to FIGURE 2, it will be seen that a top surface of the armature pivot post 26 defines a ledge 48 which is fiush with the top of the drive lever hub 28, and that the armature shoulder 43 extends forwardly over this ledge to be confined between it and the underside of a spring retaining plate .9 fixed to the electromagnet core and extending forwardly over the top of the shoulder 50 toward the pivot axis of the armature. A locating lug St) on the pivot post, projecting upwardly from the forward side of the post ahead of the spring 36, has a reduced extremity 5i engaged in a hole in the forward portion of the retaining plate to hold the same in proper relation to the armature.

The spring blade 36 is loosely confined edgewise between the ledge 48 at the top of the armature pivot post and the underside of the retaining plate 49, and enough of that portion of the bushing 27 that extends above the hub of t .e drive lever is cut away down to the level of the ledge 48 so as to accommodate the spring. As seen best in FIGURE 3, the forwardly curled end portions of the spring 36 engage reduced diameter portions of their anchor posts so that the latter also serve to prevent edgewi -e displacement of the spring.

The embodiment of the invention seen in FIGURE 8 illustrates how a pair of individual spring arms 53 can be employed to limit oscillation of the armature and to cushion the same as it reaches its limits of motion. These arms have their remote ends fixed to their respective anchor posts 37-38 in any suitable manner, and their free end portions extend toward one another and lightly engage the convex surface 41 on the armature shoulder 49 when the armature is in its center position shown.

Regardless of the direction in which the armature oscillates on its pivot post, its shoulder 40 will rock along one or the other of the spring arms toward the anchored end thereof, to encounter only slight resistance to initial motion out of its center position, but to encounter abruptly increasing resistance as the shoulder bears upon portions of the spring arms close to their anchored ends. The motion of the armature will again be interrupted as the force with which the spring arms resist rocking motion of the armature equals the impositive torsional magnetomotive force exerted upon the armature by the motor.

In each embodiment, of course, the spring blade or spring arms also define the limits of the reciprocatory motion imported to the movable cutting blade 13 by the drive lever on the armature. Also, the restoring force of the springs is available at each instant of flux reversal to start the armature moving in the opposite direction.

From the foregoing description, together with the accompanying drawings, it will be apparent that this invention features improved spring stop means for the armature of a vibratory motor, which spring means is characterized by a spring rate that increases in a gradually ascending curve that rises abruptly at the end of the armature stroke to limit the stroke and cushion the armature as it reaches its limits of motion.

What is claimed as my invention is:

I. In combination with a member which is mounted for rocking motion in opposite directions, past a center position of the member:

(A) shoulder means on said member extending to opposite sides of said axis and facing toward a plane containing said axis, so that the shoulder means at one side of the axis moves toward said plane while the shoulder means at the other side of the axis moves away from said plane during rocking of said member in either direction away from its central position; and

(B) resilient means arranged to be acted upon by said shoulder means during rocking of said member in either direction away from its central position and adapted to offer rapidly increasing resistance to rocking motion of said member through lateral zones at each side of the central position of said member and to thereafter provide substantially non-yieldable stop means by which the limits of rocking motion of said member are defined.

2. The combination of claim 1, wherein said resilient means is adapted to permit rocking motion of said member through an intermediate zone substantially without hindrance therefrom.

3. The combination of claim 2, wherein said resilient means comprises a spring blade bearing upon the shoulder means at each side of said axis, and having a fixed end remote from said axis, an easily fiexible portion extending toward said axis, and a substantially non-yieldable portion directly adjacent to its anchored end.

4. The combination of claim 2, wherein said resilient means comprises a beam spring having fixed ends at opposite sides of and remote from said axis, an easily flexible portion extending through said intermediate zone, and substantially non-yieldable portions adjacent to its anchored ends.

5. The combination of claim 4, wherein said shoulder means has a continuous convexly curved surface which bears against the beam spring and subsantially rolls therealong toward the opposite fixed ends thereof during back and forth rocking motion of said member.

6. In apparatus of the character described:

(A) a member which is mounted to rock in opposite directions about a fixed axis, past a center position of said member;

(B) a beam spring extending crosswise of said axis and having its opposite ends anchored;

(C) and shoulder means on said member, against which the spring acts, and which is shaped to substantially roll in either direction along the spring toward one or the other anchored end thereof as said member is rocked away from its center position to cause the spring to increasingly resist such rocking motion and to serve as a stop for said member when the shoulder means thereof encounters the least flexible portions of the spring adjacent to its anchored ends.

7. In combination with a member which is constrained to rock back and forth about a fixed axis, past a center position of said member:

(A) impositive drive means for applying limited torsion forces alternately in opposite directions to said member and at regular intervals to effect oscillatory motion thereof past its center position;

(B) a shoulder portion on said member at each side of said axis, which shoulder portions face in the same direction with respect to a plane containing said axis and are carried in opposite directions during rocking of the member in either direction;

(C) and resilient means cooperable with said shoulder portions and adapted to permit substantially free rocking of said member in either direction in a zone extending a distance to each side of its center position but to resist rocking of the member beyond said zone with a force that rises substantially abruptly to a value equaling the torsional force applied to the member by said impositived drive means, whereby said resilient means serves to limit rocking motion of the member and to also cushion the same as it reaches its limits of motion.

8. In combination with a vibratory motor having a permanent magnet armature mounted to oscillate about a fixed axis past a center position of the armature, and electromagnetic means to impositively eifect such oscilla tion of the armature, means to limit oscillatory motion of the armature and to cushion the same as it approaches its limits of motion, comprising:

(A) a pair of fixed anchor members equidistantly spaced to opposite sides of the armature axis;

(B) a shoulder on the armature at each side of said axis, said shoulders having convex surfaces which extend substantially equal distances outwardly of the armature axis and face toward but recede from a plane containing said anchor members;

(C) and spring blade means having arms connected with the anchor members and extendin toward the armature axis to cooperate with said shoulders, the portions of the arms remote from said anchor members being adapted to substantially lightly resist oscillatory motion of the armature in a zone extending a short distance to each side of its center position, and portions of the arms nearer the anchor members being adapted to yielding resist oscillatory motion of the armature beyond said zone with a force that rises substantially abruptly to a value equaling the magnetornotive force exerted on the armature as each shoulder portion nears its adjacent anchor member, so as to limit motion of the armature and cushion the same as it nears its limits of motion.

9. In combination with a vibratory motor having a permanent magnet armature mounted to oscillate about a fixed axis past a center position of the armature, and electromagnetic means to impositively etfect such oscillation of the armature, means to limit oscillatory motion of the armature and to cushion the same as it approaches its limits of motion, comprising:

(A) a shoulder on the armature having a convex surface that is tangent to a plane containing the armature axis in the center position of the armature, said surface extending equal distances to opposite sides of said axis and receding from said plane towards the lateral extremities of the shoulder;

(B) a pair of anchor members disposed substantially on said plane and opposite the outer portions of said shoulder;

(C) and a single spring blade extending lengthwise over said shoulder and having its opposite ends engaged with said anchor members, and along which said shoulder substantially rocks toward the anchor member at either end of the spring blade during oscillatory motion of the armature, to yieldingly resist such rocking motion of the armature with a force that rises substantially abruptly to a value equaling the magnetomotive force exerted on the armature as the shoulder approaches each anchor member in turn, so as to limit oscillatory motion of the armature and cushion the same as it nears its limits of motion.

10. A hair clipper having a reciprocable cutting blade and a vibratory motor to impart reciprocatory motion to the blade, characterized by the following:

(A) that the motor comprises an armature constrained to oscillatory motion about a fixed axis, and having a driver thereon operatively connected with the cutting blade to reciprocate the same during oscillation of the armature;

(B) that a pair of fixed anchor members are equidistantly disposed at opposite sides of the armature axis and substantially on a plane containing said axis;

(C) that the armature has a convex shoulder thereon defining a rocker which extends to opposite sides of said axis and is substantially tangent to said plane in one position of the armature at which the surface of its rocker recedes from said plane in directions toward the anchor members;

(D) and that a spring blade has its ends connected with the anchor members and extends lengthwise over said rocker to have the latter engage portions of the blade progressively closer to first one and then the other anchor member as the armature oscillates in opposite directions past said one position thereof, and which blade is adapted to yieldingly resist oscil latory motion of the armature with a force that rises abruptly as the rocker engages portions thereof near the anchor members, to a value equaling the torsional force exerted on the armature by the motor, so as to limit motion of the armature and the cutting References Cited UNITED STATES PATENTS 11/1950 Collins et a1. 31029 XR 3/1954 Zaug ZOO-16 Lebcr 2671 XR Sauer 335274 XR Blumenstock et a1. 31029 Sauer 335-274 MILLTON O. HIRSHFIELD, Primary Examiner. D. F. DUGGAN, Assistant Examiner. 

8. IN COMBINATION WITH A VIBRATORY MOTOR HAVING A PERMANENT MAGNET ARMATURE MOUNTED TO OSCILLATE ABOUT A FIXED AXIS PAST A CENTER POSITION OF THE ARMATURE, AND ELECTROMAGNETIC MEANS TO IMPOSITIVELY EFFECT SUCH OSCILLATION OF THE ARMATURE, MEANS TO LIMIT OSCILLATORY MOTION OF THE ARMATURE AND TO CUSHION THE SAME AS IT APPROACHES ITS LIMITS OF MOTION, COMPRISING: (A) A PAIR OF FIXED ANCHOR MEMBERS EQUIDISTANTLY SPACED TO OPPOSITE SIDES OF THE ARMATURE AXIS; (B) A SHOULDER ON THE ARMATURE AT EACH SIDE OF SAID AXIS, SAID SHOULDERS HAVING CONVEX SURFACES WHICH EXTEND SUBSTANTIALLY EQUAL DISTANCES OUTWARDLY OF THE ARMATURE AXIS AND FACE TOWARD BUT RECEDE FROM A PLANE CONTAINING SAID ANCHOR MEMBERS; (C) AND SPRING BLADE MEANS HAVING ARMS CONNECTED WITH THE ANCHOR MEMBERS AND EXTENDING TOWARD THE ARMATURE AXIS TO COOPERATE WITH SAID SHOULDERS, THE PORTIONS OF THE ARMS REMOTE FROM SAID ANCHOR MEMBERS BEING ADAPTED TO SUBSTANTIALLY LIGHTLY RESIST OSCILLATORY MOTION OF THE ARMATURE IN A ZONE EXTENDING A SHORT DISTANCE TO EACH SIDE OF ITS CENTER POSITION, AND PORTIONS OF THE ARMS NEARER THE ANCHOR MEMBERS BEING ADAPTED TO YIELDING RESIST OSCILLATORY MOTION OF THE ARMATURE BEYOND SAID ZONE WITH A FORCE THAT RISES SUBSTANTIALLY ABRUPTLY TO A VALUE EQUALING THE MAGNETOMOTIVE FORCE EXERTED ON THE ARMATURE AS EACH SHOULDER PORTION NEARS ITS ADJACENT ANCHOR MEMBER, SO AS TO LIMIT MOTION OF THE ARMATURE AND CUSHION THE SAME AS IT NEARS ITS LIMITS OF MOTION. 